Process for the preparation of an insoluble tobacco sheet or web



PROCESS FOR THE PREPARATION OF AN INSOLUBLE TOBACCO SHEET OR WEB Lennart 0. Pihl, Solna, Sweden, assignor to Arenco Aktiebolag, Stockholm, Sweden, a joint-stock company of Sweden No Drawing. Filed June 11, 1959, Ser. No. 819,547 Claims priority, application Sweden June 30, 1958 5 Claims. (Cl. 131-140) The invention relates to a process for the preparation of a water-resistant web or sheet from finely divided tobacco having the taste of natural whole leaf tobacco.

It is known, when manufacturing artificial tobacco products, to mix finely divided or powdered tobacco leaves or parts of such leaves with water, cast the resultrng suspension on to a plate and allow it to dry so as to prov1de a tobacco sheet. The tobacco powder, however, does not contain sufiicient fibres or adhesives to give the web or sheet the required strength, and accordingly adhesive binders must be added. It is, of course, desirable to limit the addition of such extraneous substances as far as possible, and the substances should not affect the taste of the product manufactured.

The most commonly used binder has been a cellulose adhesive which certainly affects the taste very little, but involves the great disadvantage that the sheet becomes water-soluble. The web or sheet is used wet when manufacturing both cigarettes and cigars, and must have a certain wet strength. In order to maintain this strength when the sheet is wet, a water-insoluble hinder (or a water-soluble binder treated in such a manner that it becomes Water-insoluble) must be used. It is well known that a soluble binder can be rendered insoluble in several different ways, for example by adding a hardener, such as glyoxal, to a cellulose, such as carboxymethyl cellulose (CMC), which hardner reacts with the cellulose and converts it into an insoluble form. The cellulose can also be converted to an insoluble form by precipitating the CMC-acid or an insoluble salt thereof, for example copper, magnesium or aluminum salt. The required insolubility can also be obtained if the CMC-acid itself is used as a binder by adding an acid stronger thanthe CMC- acid to lower the pH-value of the tobacco paste below In the latter case the acid may either be precipitated from a solution of a binder in water by means of a stronger acid, for example sulphuric acid, and then be washed and dispersed in water, or it may be precipitated directly in a composition of finely divided tobacco and a binder in water and then be dispersed together with the finely divided tobacco.

Irrespective of how the CMC-acid is obtained, the pI-l-value of the tobacco composition must be sufficiently low to maintain the CMC-acid in a solid form so as to provide an insoluble tobacco sheet. The tobacco sheet will consequently be very acid, and this results in deterioration in taste, aroma and burning properties. Moreover, this deterioration also results when the insolubility is obtained by precipitating the acid with metal ions, there being considerable deterioration in burning properties of the sheet. The small quantities of additives such as glyoxal that can be used without giving rise to deterioration in the taste of the sheet have given unsatisfactory insolubility.

Salts of alginic acid, which can be converted to an insoluble form in the same manneras CMC, have also been proposed as binding agents for tobacco sheets. The alginic acid is precipitated at a higher pH-value (approximately 4 to 5) than the CMC-acid and, accordingly, it has certain advantages over the CMC-acid in the manufacture of insoluble tobacco sheets.

It is, however, very diflicult to mix a soluble alginate (for example, sodium alginate) and tobacco powder as the powder, due to its high alkaloid content, reacts with the alginate during the mixing and forms a precipitate which makes it difficult to form a film from the mixture.

According to the invention the above disadvantages have been eliminated by using a combination of an algimate and CMC as a binding agent for the tobacco powder so as to obtain an insoluble sheet or web of tobacco. Thus the cellulose binder (CMC) and, for example, sodium alginate may be mixed with water and the finely divided tobacco added. A reaction between the soluble salts of the tobacco and the alginic acid is thus prevented and a homogeneous paste of tobacco and binder results. If the pH-value of this paste is adjusted to between 3 and 4 by means of, for example, citric acid an insoluble sheet will be obtained upon drying a cast film.

The invention accordingly provides a process for the preparation of an insoluble tobacco sheet or web, which process comprises mixing finely divided tobacco with water and a soluble alginate-carboxymethyl cellulose binder containing at least 10% by weight of the alginate, homogenizing the mixture, adding an acid to adjust the pH to 3-4, spreading or casting the mixture in the form of a thin film, and drying the film to form a sheet or web.

Small quantities of weak organic acids which enhance the taste of the tobacco are preferably used for adjusting the pI-Lvalue of the mixture. Organic acids such as oxalic, citric and formic acids are present in tobacco in its natural condition, and give a neutral taste to the tobacco when smoked.

[t is also advantageous that the pH-value need not be lower than 3. Below this value the tobacco acts as a heavy buffer and requires a strong acid, for example nitric acid, to lower the pl-i-value to 2.6 so as to provide an insoluble sheet when using CMC. The addition of even a small percentage of an alginate to CMC yields an insoluble sheet, although the pH is not low enough ticizer such as glycerine or ethylene glycol (which tend to increase the solubility of the film) also have good water-insolubility. An addition of at least 10% alginate to CMC has proved to give a very good insolubillty to the sheet when the pH-value of the tobacco paste is adjusted to below 4.0. The amount of alginate added is suitably between 10% and 30% by Weight for common types of tobacco, but certain types of tobacco require a considerably higher percentage of alginate so as to provide the characteristics required.

The following example illustrates the invention.

Example 8 g. of stripped and ground tobacco passing a 140 mesh screen (U.S.) was sludged in 40 ml. of Water and mixed with a solution of 1.5 g. of CMC (for example Cellufix L900) and 0.5 g. of an alginate (for example Protanal L) in 50 ml. of water. The mixture was homogenized, 1.75 ml. of glycerine were added and the pH was then adjusted to 3.5 by adding a saturated aqueous solution of citric acid. The resulting paste was spread on a platen and allowed to dry at an elevated temperature, for example C. After drying, a film of tobacco with good water-insolubility was removed from the platen; it was suitable for example, for cigar wrappers.

I claim:

1. A process for the preparation of an insoluble tobacco sheet or Web, which process comprises mixing finely divided tobacco with Water and a mixture of a Water soluble alginate and'carboxymethyl cellulose constituting a binder containing at least 10% by Weight of the alginate, homogenizing the mixture, adding an acid to adjust the pH to 34, spreading or casting the mixture in the form of a thin film, and drying the film to form a sheet or web.

2. A process as claimed in claim 1, wherein the alginate is sodium alginate.

3. A process as claimed in claim 1, wherein the acid is an organic acid. 7

' 4. A process as claimed in claim 1 whereina plasticizer is added to the mixture.

5. A process as claimed in claim 4, wherein the plasticizer is selected from the group consisting of glycerine, and, ethylene glycol.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR THE PREPARATION OF AN INSOLUBLE TOBACCO SHEET OR WEB, WHICH PROCESS COMPRISES MIXING FINELY DIVIDED TOBACCO WITH WATER AND A MIXTURE OF A WATER SOLUBLE ALGINATE AND CARBOXYMETHYL CELLULOSE CONSTITUTING A BINDER CONTAINING AT LEAST 10% BY WEIGHT OF THE ALGINATE, HOMOGENIZING THE MIXTURE, ADDING AN ACID TO ADJUST THE PH TO 3-4, SPREADING OR CASTING THE MIXTURE IN THE FORM OF A THIN FILM, AND DRYING THE FILM TO FORM A SHEET OR WEB. 